Newton's laws

Objects can experience different forms of the frictional force: static friction, maximum static friction, and kinetic friction.

In the question below there is a list of four facts about each of these forces. Each list is missing two pieces of information. Complete the lists by selecting the correct choices.

Objects can experience different forms of the frictional force: static friction, maximum static friction, and kinetic friction.

In the question below there is a list of four facts about each of these forces. Each list is missing two pieces of information. Complete the lists by selecting the correct choices.

Define the term normal force using the dropdown menus below.

Define the term normal force using the dropdown menus below.

Define tension using the dropdown menus below.

Define tension using the dropdown menus below.

Define the coefficient of static friction using the dropdown menus below.

Define the coefficient of static friction using the dropdown menus below.

There are several different types of frictional force in mechanics.

Define frictional force using the dropdown menus below.

There are several different types of frictional force in mechanics.

Define frictional force using the dropdown menus below.

Luyanda is sitting at a desk and stands up quickly. As she stands, she tilts the desk and a book almost slips off the desk. If she had tilted the desk any further, the book would have slipped off.

What specific type of frictional force is involved in the above scenario?

A plain wooden chair lies abandoned in a flat school corridor.

What specific type of frictional force is involved in the above scenario?

Amadi is investigating the motion of a crate as it slides to the left along a rough horizontal surface.

The following force diagram shows all the forces exerted on the crate except for the normal force.

Which one of the following force diagrams shows the correct size and direction of the normal force $\vec{F}_{\text{N}}$?

A

B

C

D

Chichi is investigating the motion of a box as it slides up a rough wooden ramp.

The following free-body diagram shows all the forces exerted on the box except for the normal force.

Which one of the following free-body diagrams shows the correct size and direction of the normal force $\vec{F}_{\text{N}}$?

A

B

C

D

Mzwandile is investigating the motion of a box as it slides up a rough wooden ramp.

The following force diagram shows all the forces exerted on the box.

Mzwandile now increases $\alpha$, the angle of the ramp.

Will the magnitude of the normal force experienced by the box increase, decrease, or remain the same? Give a reason for your answer.

Bridget is investigating the motion of an object as it slides up a rough wooden ramp.

The following free-body diagram shows all the forces exerted on the object.

Bridget now decreases $\alpha$, the angle of the ramp.

Will the magnitude of the normal force experienced by the object increase, decrease, or remain the same? Give a reason for your answer.

Kate is investigating the motion of an object as it slides to the left along a rough horizontal surface.

The following free-body diagram shows all the forces exerted on the object.

Kate now pulls on the object with a force that is angled out of the surface to the left.

Will the magnitude of the normal force increase, decrease, or remain the same? Give a reason for your answer.

Thato is investigating the motion of an object as it slides to the left along a rough horizontal surface.

The following force diagram shows all the forces exerted on the object.

Thato now pushes on the object with a force that is angled into the surface to the left.

Will the magnitude of the normal force increase, decrease, or remain the same? Give a reason for your answer.

The following free-body diagram shows five forces acting on an object that is in contact with a wall.

Which one of the forces represents the normal force?

The following free-body diagram shows five forces acting on an object that is in contact with a horizontal surface.

Which one of the forces represents the normal force?

The normal force $(F_{\text{N}})$, the coefficient of kinetic friction $({\mu}_{\text{k}})$, and the kinetic frictional force $(f_{\text{k}})$ are three important quantities in mechanics.

Which one of the following equations correctly represents the relationship between these quantities?

The kinetic frictional force $(f_{\text{k}})$, the normal force $(F_{\text{N}})$, and the coefficient of kinetic friction $({\mu}_{\text{k}})$ are three important quantities in mechanics.

Which one of the following equations correctly represents the relationship between these quantities?

A book is at rest on the surface of a rough plastic desk. Chike pulls on the book and the book slides along the surface. The value of maximum static friction for the book and the table is $\text{11}\ \text{N}$. Below is the force diagram showing all forces acting on the book.

1. After Chike starts pulling on the book, what type of frictional force does the book experience?
2. What can we say about the magnitude of the frictional force exerted on the book?

A box is at rest on the surface of a rough wooden desk. Atinuke pulls on the box, but the box will not shift from its position. Atinuke can tell that even if she pulled harder, it would still not move. The value of maximum static friction for the box and the table is $\text{80}\ \text{N}$. Below is the force diagram showing all forces acting on the box.

1. After Atinuke starts pulling on the box, what type of frictional force does the box experience?
2. What can we say about the magnitude of the frictional force exerted on the box?

A box is at rest on a rough surface. It experiences a normal force of magnitude $\text{206}\ \text{N}$. The coefficient of static friction between the surface and the box $(\mu_{\text{s}})$ is $\text{0,52}$.

What is the magnitude of the maximum static frictional force ($f_{\text{s}}^{\text{max}}$)?

A box is at rest on a rough surface. It experiences a normal force of magnitude $\text{185}\ \text{N}$. The magnitude of the maximum static frictional force $(f_{\text{s}}^{\text{max}})$ is $\text{66,6}\ \text{N}$.

What is the coefficient of static friction ($\mu_{\text{s}}$)?

Bukelwa applies a pushing force to a bookshelf that is initially at rest on a rough horizontal surface. The force that Bukelwa applies is parallel to the surface.

The following is a graph of the magnitude of the frictional force $(f)$ experienced by the bookshelf plotted against the magnitude of the applied pushing force $(F_{\text{push}})$.

Graphs tell stories! The table below tells the story of the graph in four parts, but in the wrong order. Match each part of the story with a label from the graph (A - D).

Emmanuel applies a pushing force to a bookshelf that is initially at rest on a rough horizontal surface. The force that Emmanuel applies is parallel to the surface.

The following is a graph of the magnitude of the frictional force $(f)$ experienced by the bookshelf plotted against the magnitude of the applied pushing force $(F_{\text{push}})$.

Graphs tell stories! The table below tells the story of the graph in four parts, but in the wrong order. Match each part of the story with a label from the graph (E - H).

Umar is investigating the motion of a crate as it slides up a rough wooden ramp.

The following free-body diagram shows all the forces exerted on the crate.

Umar now decreases $\alpha$, the angle of the ramp.

Will the magnitude of the kinetic frictional force experienced by the crate increase, decrease, or remain the same? Give a reason for your answer.

Gift is investigating the motion of a crate as it slides up a rough wooden ramp.

The following free-body diagram shows all the forces exerted on the crate.

Gift now increases $\alpha$, the angle of the ramp.

Will the magnitude of the kinetic frictional force experienced by the crate increase, decrease, or remain the same? Give a reason for your answer.

Two objects are sliding along two horizontal surfaces.

The only difference between the two objects is that Object A has a greater mass than Object B. The two horizontal surfaces are identical.

Which object will experience the smaller frictional force? Select a reason for your answer from the table below.

A lower mass...

Two objects are sliding along two horizontal surfaces.

The only difference between the two objects is that Object A is made from a smoother material than Object B. The two horizontal surfaces are identical.

Which object will experience the greater frictional force? Select a reason for your answer from the table below.

A greater roughness...

Chiamaka applies a pushing force to a table that is initially at rest on a rough horizontal surface. The force that Chiamaka applies is parallel to the surface.

The paragraphs below describe how the frictional force changes as Chiamaka pushes harder. Use the drop-down menus below to complete the paragraphs.

Chizoba applies a pulling force to a couch that is initially at rest on a rough horizontal surface. The force that Chizoba applies is parallel to the surface.

The paragraphs below describe how the frictional force changes as Chizoba pulls harder. Use the drop-down menus below to complete the paragraphs.

Two boxes are sliding down inclined planes.

The boxes are identical. The only difference between the two inclined planes is that Plane A is made from a rougher material than Plane B.

Which box will experience the smaller frictional force? Give a reason for your answer.

Two boxes are sliding down inclined planes.

The only difference between the two boxes is that Box A has a greater mass than Box B. The two inclined planes are identical.

Which box will experience the greater frictional force? Give a reason for your answer.

Nthabiseng is investigating the motion of a box as it slides to the left along a rough horizontal surface.

The following force diagram shows all the forces exerted on the box.

Nthabiseng now pushes the box perpendicularly into the surface.

Will the magnitude of the kinetic frictional force experienced by the box increase, decrease, or remain the same? Give a reason for your answer.

Gabisile is investigating the motion of a crate as it slides to the left along a rough horizontal surface.

The following force diagram shows all the forces exerted on the crate.

Gabisile now pushes the crate perpendicularly into the surface.

Will the magnitude of the kinetic frictional force experienced by the crate increase, decrease, or remain the same? Give a reason for your answer.

Marcel applies a pulling force to a table that is initially at rest on a rough horizontal surface. The force that Marcel applies is parallel to the surface.

The following is a graph of the magnitude of the frictional force experienced by the table plotted against the magnitude of the applied pulling force.

Match each of the descriptions in the table below with the correct label in the graph (P - T).

Ajibike applies a pushing force to a couch that is initially at rest on a rough horizontal surface. The force that Ajibike applies is parallel to the surface.

The following is a graph of the magnitude of the frictional force experienced by the couch plotted against the magnitude of the applied pushing force.

Match each of the descriptions in the table below with the correct label in the graph (D - H).

Adapted from DBE Nov 2015 Grade 11, P1, Q3
Physical constants · Physics formulas

A block of mass $m$ is placed on a rough horizontal surface. A constant force $(\vec{F})$ pushes the block, but the block remains at rest as shown in the diagram below. The coefficient of static friction between the block and the surface is $\mu_{\text{s}}$. If the magnitude of the applied force were any larger, the block would begin to move.

The force is changed to one of the same magnitude but in the direction shown in the diagram below. The block and rough surface stay the same.

Describe what will happen to the block. Give a reason for your answer.

Adapted from DBE Nov 2015 Grade 11, P1, Q3
Physical constants · Physics formulas

A block of mass $m$ is placed on a rough horizontal surface. A constant force $(\vec{F})$ pushes the block, but the block remains at rest as shown in the diagram below. The coefficient of static friction between the block and the surface is $\mu_{\text{s}}$. If the magnitude of the applied force were any larger, the block would begin to move.

The force is changed to one of the same magnitude but in the direction shown in the diagram below. The block and rough surface stay the same.

Describe what will happen to the block. Give a reason for your answer.

Two boxes are sliding down two slopes.

Box A on Slope A

Box B on Slope B

There are only two differences.

1. Slope A is inclined at a smaller angle to the horizontal than Slope B.
2. Slope A is made from a rougher material than Slope B.

Which box will experience the smaller kinetic frictional force?

Two boxes are sliding down two slopes.

Box A on Slope A

Box B on Slope B

There are only two differences.

1. Box A is lower on the slope than Box B.
2. Box A has a smaller contact area with the slope than Box B.

Which box will experience the greater kinetic frictional force?

Chijindum applies a pulling force to a crate that is initially at rest on a rough horizontal surface. The force that Chijindum applies is parallel to the surface.

Chijindum gradually increases the magnitude of the pulling force.

The following is a graph of the magnitude of the frictional force $(f)$ experienced by the crate plotted against the magnitude of the applied pulling force $(F_{\text{pull}})$.

The graph shows the relationship between the two parallel forces experienced by the box. The force diagram below is also a way of representing the relationship between the parallel forces at a given point.

Match the force diagram with a label from the graph (P - S).

Chibuike applies a pulling force to a bookshelf that is initially at rest on a rough horizontal surface. The force that Chibuike applies is parallel to the surface.

Chibuike gradually increases the magnitude of the pulling force.

The following is a graph of the magnitude of the frictional force $(f)$ experienced by the bookshelf plotted against the magnitude of the applied pulling force $(F_{\text{pull}})$.

The graph shows the relationship between the two parallel forces experienced by the box. The force diagram below is also a way of representing the relationship between the parallel forces at a given point.

Match the force diagram with a label from the graph (W - Z).

A block of wood weighing $\text{32}\ \text{N}$ is placed on a rough, flat surface and a rope is tied to it. The tension in the rope can be increased to $\text{16,1}\ \text{N}$ before the block starts to slide. A force of $\text{12,6}\ \text{N}$ will keep the block moving at constant speed once it has been set in motion. Determine the coefficients of static and kinetic friction.

A toy car weighing $\text{80}\ \text{N}$ is placed on a rough, flat surface and a rope is tied to it. The tension in the rope can be increased to $\text{43,2}\ \text{N}$ before the car starts to slide. A force of $\text{30,3}\ \text{N}$ will keep the car moving at constant speed once it has been set in motion. Determine the coefficients of static and kinetic friction.

Joanna pushes a crate across a rough floor. She observes the crate slow down as it slides across the rough floor.

Joanna's friend, Jacques, makes four statements about the nature of the frictional force that acts on the crate.

1. The kinetic frictional force always opposes the relative motion between two surfaces sliding past each other.
2. The frictional force depends on the speed of the crate.
3. The frictional force arises from tiny bumps in both surfaces which opposes relative motion.
4. The frictional force comes from the electrostatic force.

Help Joanna classify each of these statements as true or false.

Mpho shoves a crate across a rough floor. He observes the crate slow down as it slides across the rough floor.

Mpho's friend, Nicole, makes four statements about the nature of the frictional force that acts on the crate.

1. The frictional force comes from the gravitational force.
2. The kinetic frictional force always opposes the relative motion between two surfaces sliding past each other.
3. The frictional force arises from tiny bumps in both surfaces which opposes relative motion.
4. The frictional force comes from the electrostatic force.

Help Mpho classify each of these statements as true or false.

A box is sliding across a rough surface. It experiences a normal force of magnitude $\text{952}\ \text{N}$. The coefficient of kinetic friction between the surface and the box $(\mu_{\text{k}})$ is $\text{0,26}$.

What is the magnitude of the kinetic frictional force ($f_{\text{k}}$)?

A box is sliding across a rough surface. It experiences a normal force of magnitude $\text{450}\ \text{N}$. The magnitude of the kinetic frictional force $(f_{\text{k}})$ is $\text{159,8}\ \text{N}$.

What is the coefficient of kinetic friction ($\mu_{\text{k}}$)?

Define a free-body diagram using the dropdown menus below.

Define a free-body diagram using the dropdown menus below.

A number of different forces are acting on a crate. Gabisile draws the following diagram to show all these forces.

Did Gabisile draw a free-body diagram or a force diagram?

Give a reason for your answer from the table below.

A number of different forces are acting on a crate. Gabisile draws the following diagram to show all these forces.

Did Gabisile draw a free-body diagram or a force diagram?

Give a reason for your answer from the table below.

A system of two blocks is pulled to the left across a rough surface.

Angelique tries to draw a force diagram to show all the forces acting on the block on the left.

This is the diagram that she draws:

The diagram has the correct number of forces, but there is a problem with the diagram! What mistake did Angelique make?

A box is in a lift which is accelerating up.

Adebiyi tries to draw a free-body diagram to show all the forces acting on the box.

This is the diagram that he draws:

The diagram has the correct number of forces, but there is a problem with the diagram! What mistake did Adebiyi make?

A system of two blocks is pulled up a smooth inclined plane.

The string joining the two blocks is inextensible (it can't be stretched) and it is pulled tight.

Jezile draws a diagram to show all the forces acting on one of the blocks.

This is the diagram that she draws:

Which one of the options below best describes the diagram that Jezile drew?

A system of two blocks is pulled down a smooth ramp.

The string joining the two blocks is inextensible (it can't be stretched) and it is pulled tight.

Chukwuma draws a diagram to show all the forces acting on one of the blocks.

This is the diagram that he draws:

Which one of the options below best describes the diagram that Chukwuma drew?

Box $\text{1}$ is connected to Box $\text{2}$ by a light inextensible string. The same type of string is attached to Box $\text{2}$, run over a light frictionless pulley, and connected to a motor.

The motor pulls the system up a smooth ramp inclined at an angle $\alpha$ to the horizontal. The motor applies a constant force which causes the system to accelerate. The force applied by the motor is parallel to the ramp as shown in the diagram below. Ignore all forms of friction.

Draw labelled free-body diagrams indicating all the forces acting on the both boxes.

How many forces should there be in these diagrams?Remember that a free-body diagram should contain actual forces, not components of forces.

Box $\text{1}$ is connected to Box $\text{2}$ by a light inextensible rope. The same type of rope is attached to Box $\text{2}$, run over a light frictionless pulley, and connected to a motor.

The motor pulls the system up a smooth plane inclined at an angle $\alpha$ to the horizontal. The motor applies a constant force which causes the system to accelerate. The force applied by the motor is parallel to the plane as shown in the diagram below. Ignore all forms of friction.

Draw labelled free-body diagrams showing all the forces acting on the both boxes.

How many forces should there be in these diagrams?Remember that a free-body diagram should contain actual forces, not components of forces.

Block 1 is connected to Block 2 by a light inextensible string. The system is pulled up a rough ramp inclined at $\alpha$ to the vertical, by means of a constant force parallel to the ramp as shown in the diagram below. The magnitude of the kinetic frictional force between the surface and Block $\text{1}$ is $f_{\text{k}, 1}$.

Draw a labelled free-body diagram indicating all the forces acting on Block 1 as it moves up the ramp.

The free-body diagram given below contains a mistake. There is a problem with one of the forces.

Compare your free-body diagram to the given diagram to work out which force is the problem and what the mistake is.

Crate 1 is connected to Crate 2 by a light inextensible rope. The system is pulled up a smooth plane inclined at $\alpha$ to the horizontal, by means of a constant force parallel to the plane as shown in the diagram below. All forms of friction can be ignored.

Draw a labelled free-body diagram indicating all the forces acting on Crate 1 as it moves up the plane.

The free-body diagram given below contains a mistake. There is a problem with one of the forces.

Compare your free-body diagram to the given diagram to work out which force is the problem and what the mistake is.

A system of two blocks is pulled to the left across a rough surface.

Limpho draws the following force diagram to show all the forces acting on the block on the left.

The diagram has the correct number of forces, but one of the forces is pointing in the wrong direction. Which force is incorrect?

A system of two packages is pulled down a smooth slope.

Faruq draws the following force diagram to show all the forces acting on the higher package.

The diagram has the correct number of forces, but one of the forces is pointing in the wrong direction. Which force is incorrect?

Adapted from DBE Nov 2015 Grade 11, P1, Q3
Physical constants · Physics formulas

A $\text{70}\ \text{kg}$ block is placed on a rough horizontal surface. A constant force $(\vec{F})$ pushes the block and the block moves across the surface at a constant speed as shown in the diagram below. The coefficient of kinetic friction $(\mu_{\text{k}})$ between the block and the surface is $\text{0,42}$.

Draw a labelled free-body diagram showing all the forces acting on the block.

For each of the free-body diagrams below use the table of options (W to Z) to say if the diagram is correct or to explain why it is incorrect.

Adapted from DBE Nov 2015 Grade 11, P1, Q3
Physical constants · Physics formulas

A $\text{60}\ \text{kg}$ block is placed on a rough horizontal surface. A constant force $(\vec{F})$ pulls the block, but the block remains at rest as shown in the diagram below. The coefficient of static friction $(\mu_{\text{s}})$ between the block and the surface is $\text{0,58}$. If the magnitude of the applied force were any larger, the block would begin to move.

Draw a labelled free-body diagram showing all the forces acting on the block.

For each of the free-body diagrams below use the table of options (W to Z) to say if the diagram is correct or to explain why it is incorrect.

A gravitational force of $\vec{F}_{\text{g}} = \text{128}\ \text{N}$ is acting straight down on a block. The block is on an inclined plane with a slope inclined at an angle of $\text{34}\text{°}$ with the horizontal.

Calculate the components of the force due to gravity parallel and perpendicular to the slope.

A gravitational force of $\vec{F}_{\text{g}} = \text{176}\ \text{N}$ is acting straight down on a block. The block is on an inclined plane with a slope inclined at an angle of $\text{25}\text{°}$ with the horizontal.

Calculate the components of the force due to gravity parallel and perpendicular to the slope.

Adebankole is pushing a trolley with a constant force of $\text{48,77}\ \text{N}$. The trolley is experiencing a force due to gravity of $\text{160}\ \text{N}$. A constant frictional force of $\text{30,69}\ \text{N}$ is present.

What is the resultant force on the trolley?

Eric is pushing a trolley with a constant force of $\text{108,3}\ \text{N}$. The trolley is experiencing a force due to gravity of $\text{140}\ \text{N}$. A constant frictional force of $\text{79,54}\ \text{N}$ is present.

What is the resultant force on the trolley?

Five forces are acting on a book. The following diagram shows the scenario as seen from above.

Three of the forces are aligned along the north-south axis. The other two forces are aligned along the east-west axis.

Calculate:

1. The net force along the north-south axis.
2. The net force along the east-west axis.

Five forces are acting on a cupboard. The following diagram shows the scenario as seen from above.

Three of the forces are aligned along the east-west axis. The other two forces are aligned along the north-south axis.

Calculate:

1. The net force along the east-west axis.
2. The net force along the north-south axis.

A gravitational force of $\vec{F}_{\text{g}} = \text{174}\ \text{N}$ is acting straight down on a block on an inclined slope.

If the magnitude of the component of the gravitational force perpendicular to the slope is $\text{164,4}\ \text{N}$, what is the incline (angle) of the slope as measured from the horizontal?

A gravitational force of $\vec{F}_{\text{g}} = \text{164}\ \text{N}$ is acting straight down on a block on an inclined slope.

If the magnitude of the component of the gravitational force perpendicular to the slope is $\text{143,3}\ \text{N}$, what is the incline (angle) of the slope as measured from the horizontal?

Two forces, $\text{8}\ \text{N}$ and $\text{4}\ \text{N}$, act at an angle at the same point.

Which one of the following can be the magnitude of the resultant of these two forces?

Two forces, $\text{9}\ \text{N}$ and $\text{3}\ \text{N}$, act at an angle at the same point.

Which one of the following cannot be the magnitude of the resultant of these two forces?

Five forces are acting on an object. The following diagram shows the scenario as seen from the side.

Three of the forces are aligned along the $y$-axis. The other two forces are aligned along the $x$-axis.

Calculate the magnitude and direction of the net force exerted on the object.

Five forces are acting on a cupboard. The following diagram shows the scenario as seen from above.

Three of the forces are aligned along the east-west axis. The other two forces are aligned along the north-south axis.

Calculate the magnitude and direction of the net force exerted on the cupboard.

Crate $\text{1}$ is connected to Crate $\text{2}$ by a light inextensible rope. The same type of rope is attached to Crate $\text{2}$, run over a light frictionless pulley, and connected to a motor.

The motor pulls the system up a rough ramp inclined at an angle $\alpha$ to the horizontal. The motor applies a constant force which causes the system to accelerate. The force applied by the motor is parallel to the ramp as shown in the diagram below. Do not ignore friction.

The following table contains possible expressions for the magnitude of the net force experienced by the two crates. Identify which expression belongs with each crate.

Box $\text{1}$ is connected to Box $\text{2}$ by a light inextensible rope. The same type of rope is attached to Box $\text{2}$, run over a light frictionless pulley, and connected to a motor.

The motor pulls the system up a smooth ramp inclined at an angle $\alpha$ to the vertical. The motor applies a constant force which causes the system to accelerate. The force applied by the motor is parallel to the ramp as shown in the diagram below. Ignore all forms of friction.

The following table contains possible expressions for the magnitude of the net force experienced by the two crates. Identify which expression belongs with each crate.

Danjuma is pulling an object across the floor with a force $\vec{F}$ at an angle of $\text{18}°$ east of north. The following diagram (which is not to scale) shows the scenario as seen from above.

The component of the pulling force to the east is $\text{53}\ \text{N}$.

Calculate:

1. the magnitude of the applied pulling force.
2. the magnitude of the component of the pulling force to the north.

Peter is pulling a box across the floor with a force $\vec{F}$ at an angle of $\text{34}°$ east of north. The following diagram (which is not to scale) shows the scenario as seen from above.

The component of the pulling force to the north is $\text{225}\ \text{N}$.

Calculate:

1. the magnitude of the applied pulling force.
2. the magnitude of the component of the pulling force to the east.

Chibuike is pulling a crate across the floor with a force $\vec{F}$ at an angle of $\alpha$ to the vertical. The following diagram (which is not to scale) shows the scenario as seen from the side.

The vertical component of the pulling force is $\text{57}\ \text{N}$ and the horizontal component of the pulling force is $\text{37}\ \text{N}$.

Calculate:

1. the magnitude of the applied pulling force.
2. the angle that describes the direction of the applied pushing force.

Chukwuma is pulling a box across the floor with a force $\vec{F}$ at an angle of $\alpha$ to the vertical. The following diagram (which is not to scale) shows the scenario as seen from the side.

The vertical component of the pulling force is $\text{88}\ \text{N}$ and the horizontal component of the pulling force is $\text{53}\ \text{N}$.

Calculate:

1. the magnitude of the applied pulling force.
2. the angle that describes the direction of the applied pushing force.

Yengwayo is pulling a cupboard across the floor with a force of $\text{300}\ \text{N}$ at an angle of $\text{25}°$ to the horizontal. The following diagram (which is not to scale) shows the scenario as seen from the side.

Resolve the pulling force into horizontal $(x)$ and vertical $(y)$ components.

Kayla is pulling an object across the floor with a force of $\text{250}\ \text{N}$ at an angle of $\text{34}°$ west of north. The following diagram (which is not to scale) shows the scenario as seen from above.

Resolve the pulling force into components to the north and west.

Consider the following diagram of a bus parked on a hill:

Choose the vector which best describes the normal force acting on the bus.

Consider the following diagram of a bus parked on a hill:

Choose the vector which best describes the gravitational force acting on the bus.

A parcel is loose on the smooth back seat of a car. The driver of the car turns a corner sharply. The parcel is seen to move to one side of the car.

Classify each of the following four statements as correct reasons or incorrect reasons for why the parcel is seen to move to the side.

A box is loose on the smooth back seat of a car. The driver of the car turns a corner sharply. The box is seen to move to one side of the car.

Classify each of the following four statements as correct reasons or incorrect reasons for why the box is seen to move to the side.

Lindiwe is standing in a stationary train which suddenly starts to move. She isn't holding onto anything and falls backward!

Lindiwe falls backward because ...

Mphikeleli is standing in a stationary bus which suddenly starts to move. He isn't holding onto anything and falls backward!

Mphikeleli falls backward because ...

A book is loose on the smooth back seat of a car. The driver of the car turns a corner sharply. The book is observed to slide to one side of the car.

Which one of the following statements could not be used as reason for why the book is observed to slide to the side?

An object is loose on the smooth back seat of a car. The driver of the car turns a corner sharply. The object is seen to slide to one side of the car.

Which one of the following statements could be used as reason for why the object is seen to slide to the side?

Four different learners were asked to state what they thought Newton’s first law of motion means. Three of the learners have incorrect interpretations and one has a correct interpretation.

Which one of the following statements is correct?

Four different learners were asked to state what they thought Newton’s first law of motion means. Three of the learners have correct interpretations and one has an incorrect interpretation.

Which one of the following statements is incorrect?

Adapted from DBE Nov 2015 & 2016 Grade 11, P1, Q3
Physical constants · Physics formulas

State Newton's first law of motion in words.

Adapted from DBE Nov 2015 & 2016 Grade 11, P1, Q3
Physical constants · Physics formulas

State Newton's first law of motion in words.

Sindisiwe is driving a car along a dirt road. A horse crosses the road and Sindisiwe immediately slams on the brakes and manages to stop in time. Fortunately, Sindisiwe was wearing a seatbelt and so was unharmed.

Use appropriate physics principles to complete the paragraph below which explains the importance of seatbelts.

Luyanda is driving a car along a dirt road. A monkey crosses the road and Luyanda immediately slams on the brakes and manages to stop in time. Fortunately, Luyanda was wearing a seatbelt and so was unharmed.

Use appropriate physics principles to complete the paragraph below which explains the importance of seatbelts.

Adapted from WCED Metro Central Sep 2017 Grade 12, P1, Q1.1
Physical constants · Physics formulas

If you don't walk carefully while holding a full bowl of soup, the soup will easily spill over the edge of the bowl because of ...

Adapted from WCED Metro Central Sep 2017 Grade 12, P1, Q1.1
Physical constants · Physics formulas

If you don't walk carefully while holding a full bowl of soup, the soup will easily spill over the edge of the bowl because of ...

Use the drop-down menus below to define inertia.

Use the drop-down menus below to define inertia.

A person with a mass of $\text{110}\ \text{kg}$ and a weight of $\text{1 078}\ \text{N}$ stands on a scale (which gives a reading in newtons) inside a rocket that is accelerating downwards at $\text{1,4}\ \text{m·s$^{-2}$}$. What is the reading on the scale?

A person with a mass of $\text{100}\ \text{kg}$ and a weight of $\text{980}\ \text{N}$ stands on a scale (which gives a reading in newtons) inside a rocket that is accelerating upwards at $\text{3,4}\ \text{m·s$^{-2}$}$. What is the reading on the scale?

Mass $(m)$, net force $(F_{\text{net}})$, and acceleration $(a)$ are three important quantities in mechanics. They are related to each other through Newton's second law of motion.

Which one of the following equations correctly represents the relationship between these quantities?

Mass $(m)$, acceleration $(a)$, and net force $(F_{\text{net}})$ are three important quantities in mechanics. They are related to each other through Newton's second law of motion.

Which one of the following equations correctly represents the relationship between these quantities?